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Re: Secondary additions and corona breakout

Subject:  Re: Secondary additions and corona breakout
  Date:   Fri, 16 May 1997 02:03:12 -0400 (EDT)
  From:   richard hull <rhull-at-richmond.infi-dot-net>
    To:   Tesla List <tesla-at-pupman-dot-com>


>Interesting! quite a few years ago I tried winding a secondary made
>of numerous short lengths of enameled wire. I soldered each joint and
>coated it with gliptol if I remeber correctly, any way I do 
>distinctly remeber that when I powered up that coil I had corona 
>break out at each and every solder joint. Granted I didn't saturate 
>the windings in polyureathane as I do now but still I remeber having 
>a dickens of a time trying to stop the coronal breakout, untill I 
>finally scratched the whole idea and ever since I have only been 
>using continous lengths of wire for my secondaries. Perhaps I should 
>try it again and this time give the final coil several coats of 
>polyureathane.
>


I used to repair Nemesis after some unseen hits from a nearby, early
magnifier defeated the insulation on Nemesis' 18 magnet wire secondary. 
We
would turn the large coil on not aware of a possible problem and the
usual
12-15 foot arcs would leap forward down the lab, but in mid run a turn
or
two on the secondary would suddenly come to incandescence.  We quickly
shut
the thing down and repairs were required.  at first I would take about 4
hours and carefully replace the turn.  As this happen more and more
often
due to improved maggey designs, I started just romoving the burned turns
and
just linking the ends as in teeth with gaps in them.  My proceedure was
simple.

I would dremel out the charred form material and fill with epoxy.  after
curing I would solder the two ends togeter with a special lap joint
which
had been carefully filed, aligned and tinned.  Finally, I would take
epoxy
in a syringe and flow it under the wire by lifting it slightly with a
dental
pick and then cover the wire with epoxy.  I did this until a distinct
bump
appear out the side of the windings.  I never observed corona at a joint
and
Nemesis still jumped the full length it always had. 

 No repair ever broke down or faulted.  Still, I continued to slap the
secondary with improved magnifers and the reapirs became so numerous
that
poor Nemesis looked like a coil with acne zits!  As Nemesis was in need
of a
complete rebuild and our maggey work was rivaling Nemesis' performance
with
less power, all two coil systems were retired for the magnifier program.

Solid, stable repairs are quite possible if made with care which will
not
corona, even in the megavolt and multi-kilowatt range.


Richard Hull, TCBOR